Stepper Motors

Do you want to select the stepped setting on a variable transformer with a stepper motor?

If it is a large variac, use a cogged belt drive to reduce the motor size required to drive it. I built one once with a 1KVA variac. They also offer systems already set up to do this but it's been a long time and I'm not sure where to find them. Google it.

You need to supply more detail....is it to be controlled remotely, do you need indication, should it react very fast, should it be very exact?????

Tell us everything please, then we can help.

Steppers are easy to control with a small amount of electronics. I would suggest a small motor with a small toothed pulley, driving a large toothed pulley via a toothed belt. It will run more than fast enough and will still allow fine adjustment.

A simple circuit using an NE555 or the modern equivalent will be enough to drive the stepper driver.

Even simpler, would be a switch for direction and a push button for the steps, almost no electronic chips at all (except for the stepper driver chip SL7062 or 7 would be good).....really fine adjustment......